Lean Body Mass Calculator - Estimate Your LBM Now
This lean body mass calculator estimates how much of your body weight is lean tissue based on sex, height, and weight. Lean body mass is everything except fat, so it helps you plan protein, calories, and strength goals more accurately.
Use it as a practical baseline, then track changes over time. Pair the result with body fat estimates or progress photos to see whether your training and nutrition are building muscle while keeping fat in check. Because the formula is an estimate, focus on trends over weeks instead of a single-day number.
Quick summary
This lean body mass calculator estimates LBM from sex, height, and weight, then explains the formula and provides a lean-mass chart. The page includes examples, FAQs, and references to guide interpretation.
Lean Body Mass Calculator
Calculator
Enter your sex, height, and weight to estimate lean body mass (LBM). This uses the Boer formula, which is a common clinical estimate for adults.
Lean mass chart
The chart below shows how lean body mass changes at different body fat percentages for a 180 lb body weight. To adapt the table, simply multiply your own body weight by (1 - body fat %). This gives a quick way to sanity-check your calculated result. Higher lean mass at the same body weight generally means a lower body fat percentage.
| Body fat % | Lean mass at 180 lb | Formula used |
|---|---|---|
| 10% | 162 lb | 180 x (1 - 0.10) |
| 15% | 153 lb | 180 x (1 - 0.15) |
| 20% | 144 lb | 180 x (1 - 0.20) |
| 25% | 135 lb | 180 x (1 - 0.25) |
| 30% | 126 lb | 180 x (1 - 0.30) |
| 35% | 117 lb | 180 x (1 - 0.35) |
Formula
This calculator uses the Boer formula, a widely used equation for estimating lean body mass in adults. It requires your sex, height, and body weight. Results are in kilograms, and the calculator shows pounds for convenience. The equation is not a direct body fat test; it is a statistical estimate based on typical body proportions.
If you already know your body fat percentage, you can also estimate lean mass directly: LBM = weight x (1 - body fat %). Use the same unit for weight and the result.
Example calculation
Example: A 180 lb male who is 5'10" (70 in) tall weighs 81.6 kg and is 177.8 cm tall. Using the Boer formula: 0.407 x 81.6 + 0.267 x 177.8 - 19.2 is about 61.5 kg of lean mass.
That equals about 136 lb of lean body mass. The remaining weight (roughly 44 lb) is fat mass. Track changes in lean mass alongside your training volume and protein intake for the clearest progress signal. If the same lifter gains 5 lb of lean mass over a training cycle, the number should rise even if scale weight stays similar.
FAQ
Is lean body mass the same as fat-free mass?
They are often used interchangeably. Both represent everything in the body that is not fat, including muscle, bone, organs, and water.
Which lean body mass formula is best?
The Boer formula performs well for most adults. If you are an athlete or have access to DEXA scans, use those results for the most precise tracking.
Can hydration change my lean body mass?
Hydration influences scale weight, so the estimate can shift. For consistency, measure under similar conditions each time.
How should I use lean body mass in nutrition?
Many lifters base protein and calorie targets on lean mass. For example, you can compare LBM changes while adjusting training volume or energy intake.
Resources
Learn more about body composition basics from the CDC weight assessment overview and the ExRx body composition reference.
Related tools: BMI Calculator for Female, One Rep Max Calculator for Bench Press, and TDEE Calculator for Weight Loss. Use them together to link strength gains, body composition, and daily energy needs.